After an unsuccessful visit to the high-IQ sperm bank, Leonard (Johnny Galecki) and Sheldon (Jim Parsons) return home to find out Penny (Kaley Cuoco), a new neighbor, has moved in across the hall. Leonard immediately becomes interested in her, while Sheldon feels his friend is chasing a dream he'll never catch. Later, Leonard invites Penny to his and Sheldon's apartment, where she gets to meet their friends Howard Wolowitz (Simon Helberg), a wannabe ladies man, and Rajesh Koothrappali (Kunal Nayyar), who is so shy he cannot speak to women.
Leonard is so infatuated with Penny that, after letting her use their shower, he agrees to retrieve her TV from her ex-boyfriend Kurt (Brian Wade). However, Kurt's physical superiority overpowers Leonard and Sheldon's combined IQ of 360, and they return empty handed and depantsed. Feeling bad for them, Penny offers to take the guys to dinner, in what is the start of a new friendship.